Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/0006—Particular feeding systems
  • H01Q21/0075—Stripline fed arrays
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
  • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
  • H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
  • H01Q1/242—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use
  • H01Q1/243—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use with built-in antennas
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/52—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
  • H01Q1/521—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure reducing the coupling between adjacent antennas
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/28—Combinations of substantially independent non-interacting antenna units or systems
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q7/00—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
  • H01Q7/005—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop with variable reactance for tuning the antenna
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
  • H01Q9/04—Resonant antennas
  • H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole
  • H01Q9/42—Resonant antennas with feed to end of elongated active element, e.g. unipole with folded element, the folded parts being spaced apart a small fraction of the operating wavelength

Definitions

• the present application relates generally to communication devices, and more particularly to, multiple-input multiple-output (MIMO) antennas and wireless communication devices using MIMO antennas.
• MIMO multiple-input multiple-output
• Wireless communication devices such as WIFI 802.1 IN and LTE compliant communication devices, are increasingly using MIMO antenna technology to provide increased data communication rates with decreased error rates.
• a MIMO antenna includes at least two antenna elements. The operational performance of a MIMO antenna depends upon obtaining sufficient decoupling and decorrelation between its antenna elements. It is therefore usually desirable to position the antenna elements far apart within a device and/or to use radiofrequency (RF) shielding therebetween while balancing its size and other design constraints.
• RF radiofrequency
• the chassi plays an important role in determining the mutual coupling among the antennas, since the chassis not only acts as a ground plane, but also as a radiator shared by the multiple antennas.
• the radiation patterns are modified by the chassi, so that the angle and polarization diversities are difficult to achieve.
• the achievable performance of the multiple antenna terminals in MIMO applications may be degraded.
• Some embodiments of the present inventive concept provide an antenna including a chassi and first and second radiating elements coupled to the chassi.
• the first radiating element is configured to amplify excitation of the chassi and the second radiating element is
• CONFIRMATION COPY configured to reduce excitation of the chassi so as to reduce mutual coupling in the antenna system.
• the first radiating element may be included in a folded monopole antenna and the second radiating element may be included in a loop antenna.
• the folded monopole antenna may include the first radiating element and a strip line on the chassi, the monopole strip being coupled to the first radiating element.
• the loop antenna may include the second radiating element; a loop feeding line on the chassi, the loop feeding line being coupled to the second radiating element; and an element configured to tune a resonant frequency of the loop antenna.
• the second radiating element may be one of a semi-square loop, a meander line loop and a circular loop.
• the loop feeding line is one of a semi-square loop, an L- shaped feed and a T-shaped feed.
• a matching condition of the loop feeding line may be tuned by varying dimensions of the semi- square loop.
• the element configured to tune the resonant frequency of the loop antenna may be an interdigital capacitor. If the element used to tune the resonant frequency of the loop antenna is an interdigtial capacitor, the interdigital capacitor may be configured to tune the resonant frequency of the loop antenna by changing an arm length of the interdigital capacitor and/or a distance between arms of the interdigital capacitor.
• the element configured to tune a resonant frequency of the loop antenna is at least one of a variable capacitor and a varactor diode.
• the loop antenna may further include a hollow plastic carrier configured to support the loop antenna.
• the folded monopole antenna is located at a first end of the chassi and the loop antenna is located at a second end of the chassi, the second end of the chassi being opposite the first end of the chassi.
• the folded monopole antenna and the loop antenna are co- located at a same end of the chassi.
• the antenna system is included in a wireless communications device.
• a co-located multiple input multiple output (MIMO) antenna comprising: a chassi; a folded monopole antenna coupled to a first end of the chassi, the folded monopole antenna comprising: a first radiating element on the chassi; and a strip line on the chassi, the monopole strip being coupled to the first radiating element; and a loop antenna coupled to the first end of the chassi such that the folded monopole antenna and the loop antenna are co-located at the first end of the chassi, the loop antenna comprising: a second radiating element on the chassi; a loop feeding line on the chassi, the loop feeding line being coupled to the second radiating element; and an element configured to tune a resonant frequency of the loop antenna.
• MIMO co-located multiple input multiple output
• Some embodiments of the present inventive concept provide methods of controlling mutual coupling in an antenna system provided on a chassi.
• the method includes providing a first radiating element coupled to a first end of the chassi, the first radiating element configured to amplify excitation of the chassi; and providing a second radiating element .coupled to a second end of the chassi, the second radiating element configured to reduce excitation of the chassi.
• first and second ends of the chassi may be a same end of the chassi such that the first and second radiating elements are co-located at a same end of the chassi.
• Figure 1 is a diagram illustrating a multiple antenna system according to some embodiments of the present inventive concept.
• Figure 2 is a graph of antenna scattering parameters (Sn, S 22 and S 2 i) versus frequency that may be generated by an operational simulation of the antenna system of Figure 1 according to some embodiments of the present inventive concept.
• Figures 3A through 3D are graphs illustrating simulated radiation patterns of the antenna system of Figure 1 according to some embodiments of the present inventive concept.
• Figure 4 is a graph of antenna scattering parameters (S l l5 S 22 and S 21 ) versus frequency that may be generated by an operational simulation of the antenna system of Figure 1 for different values of a capacitor according to some embodiments of the present inventive concept.
• Figure 5 is a diagram illustrating a co-located multiple antenna system according to some embodiments of the present inventive concept.
• Figure 6 is a graph of antenna scattering parameters (Sn, S 22 and S 2 i) versus frequency that may be generated by an operational simulation of the antenna system of Figure
• FIGS 7A and 7B are diagrams illustrating various embodiments of the feeding portion of the antenna according to some embodiments of the present inventive concept.
• Figures 8A through 8C are diagrams illustrating various embodiments of the radiating loop according to some embodiments of the present inventive concept.
• Figure 9 is a block diagram of some electronic components, including an antenna system, of a wireless communication terminal in accordance with some embodiments of the present inventive concept.
• spatially relative terms such as “above”, “below”, “upper”, “lower” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Well-known functions or constructions may not be described in detail for brevity and/or clarity.
• Embodiments of the inventive concept are described herein with reference to schematic illustrations of idealized embodiments of the inventive concept. As such, variations from the shapes and relative sizes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the inventive concept should not be construed as limited to the particular shapes and relative sizes of regions illustrated herein but are to include deviations in shapes and/or relative sizes that result, for example, from different operational constraints and/or from manufacturing constraints. Thus, the elements illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the inventive concept.
• wireless terminal that includes a an antenna system, for example, a MIMO antenna, that is configured to transmit and receive RF signals in two or more frequency bands.
• the antenna may be configured, for example, to transmit/receive RF communication signals in the frequency ranges used for cellular communications (e.g., cellular voice and/or data communications), WLAN communications, and/or TransferJet communications, etc.
• design of multiple antennas for use in, for example, compact mobile terminals can be a significant challenge, especially for low frequency bands of, for example, below about 1.0 GHz.
• the chassis of these antennas is typically a shared radiator of the antennas, thus, at low frequency bands the mutual coupling among the antennas may be very strong, which degrades antenna performance, such as correlation, diversity gain, capacity and the like.
• some embodiments of the present inventive concept provide an antenna system that addresses the strong mutual coupling for two-antennas sharing a common radiating chassi.
• a magnetic-field-responsive loop antenna is used as a diversity antenna, in order to reduce shared chassis radiation with the main antenna, for example, a folded monopole antenna.
• the two antennas i.e., the magnetic loop antenna and the folded monopole, can be co-located at one edge of the chassis, which may greatly reduce the necessary space for antenna implementation on the chassi.
• some embodiments of the present inventive concept can provide high isolation, for example, of above about 20 dB; high efficiency, for example, of above about 80% for both antennas; and good diversity gains, for example, of above about 9.5 dB for switched combining at 1.0% probability for frequencies less than 1.0 GHz as will be discussed further below with respect to Figures 1 through 9 below.
• the antenna system 100 for example, a multiple input multiple output (MIMO) antenna, includes a folded monopole antenna 105 as a main antenna and a magnetic field responsive loop antenna 110 as a diversity antenna.
• the folded monopole antenna 105 and the magnetic loop antenna 110 share a chassi 115.
• the two antennas 105 and 110 are spaced apart and are located at opposite ends of the chassi 115.
• the chassi 115, or ground plane, of the antenna system 100 is made of copper.
• the chassi may be 100mm x 40mm, or the typical dimensions of a chassi in a candy-bar type mobile phone.
• chassis according to embodiments of the present inventive concept are not limited to these exemplary dimensions.
• the folded monopole antenna 105 includes a radiator, the radiator including 120 and 125, and a port 195.
• the radiator 120 and 125 is implemented on a printed circuit board (PCB) 130.
• the PCB 130 can be a thin copper layer on a Teflon laminate substrate.
• the substrate may have a permittivity of 2.45, a loss tangent of 0.003 and a thickness of about 0.8mm.
• the portion of the radiator (strip line) 125 of the folded monopole antenna 105 may be printed on the Teflon laminate substrate 130.
• the loop antenna 110 includes a feeding line 135, a radiator 140, an interdigital capacitor 145 and a port 196.
• the feeding line 135 of the magnetic field responsive loop antenna 110 is illustrated in Figure 1 as being a semi-square ring loop.
• a matching condition can be tuned by, for example, varying the dimensions of the semi- square loop feeding line 135.
• embodiments of the present invention are not limited to the feeling line 135 configuration illustrated in Figure 1.
• the feeding line 135 of the loop antenna 110 can be an 'L-shaped' feed 735' or a 'T-shaped' feed 735" as long as the impedance matching is well achieved.
• the radiator 140 of the loop antenna is also a semi- square ring loop of larger dimensions than the feeding loop 135.
• the radiator of the loop antenna 110 can be a meander line loop 840' or a circular loop 840".
• the position of the opening of the loop does not need to be in the center of the loop, it can be at any part of the loop, as illustrated in Figure 8C, 840", however, it would need to be re-matched.
• a resonant frequency of the loop antenna 110 can be tuned by, for example, changing a length of an arm 150 of the interdigital capacitor 145 and/or a distance between the arms 150 of the interdigital capacitor 145. It will be understood that these adjustments to the arms 150 of the interdigital capacitor 145 would be performed during manufacturing of the antenna system 100.
• embodiments of the present inventive concept are illustrated in Figure 1 as including an interdigital capacitor 145, embodiments of the present inventive concept are not limited to this configuration.
• the interdigital capacitor could be replaced by another element 745', 745", 845' and 845", for example, a MEMS capacitor or a varactor diode without departing from the scope of the present inventive concept.
• These embodiments may allow for tuning after the antenna system has been fabricated, i.e. during operation.
• the antenna system 100 of Figure 1 further includes a hollow carrier 155 made of, for example, plastic.
• This hollow carrier 155 may be used to support the loop antenna 110.
• a speaker and/or camera of the mobile terminal may be placed inside the hollow carrier 155 of the antenna system 100 to conserve space and allow the size of the terminal to be decreased.
• chassi 115 configured to amplify excitation of the chassi 115 and a loop antenna 110 to reduce excitation of the chassi 115 is provided in accordance with some embodiments may reduce the problem of mutual coupling among antennas on a small chassis at low
• the two antennas can also be co-located at a same side of the chassi 115 to save implementation space on the chassis of a mobile terminal. Accordingly, embodiments discussed herein can be used to address the mutual coupling problem between closely packed MIMO antennas operating at low frequencies, for example, the LTE 700MHz band.
• FIG. 2 a graph of antenna scattering parameters (Sn, S 22; Si 2 and S 2 i) versus frequency that may be generated by an operational simulation of the antenna system of Figure 1 will be discussed.
• the folded monopole antenna 105 is represented as antenna 1 and the loop antenna is represented as antenna 2.
• Sn indicated by curve 205 represents radiating element 120 of the folded monopole antenna 105 of Figure 1 and is a measure of how much power (dB) is reflected back to transceiver circuitry connected thereto.
• S 22 indicated by curve 215 represents radiating element 140 of the loop antenna circuitry connected thereto.
• S 21 S 12 (indicated by Curve 210) represents the coupling that occurs between the antenna feed ports of the radiating elements 120 and 140. As illustrated in Figure 2, a good isolation of above 30 dB is achieved using the antenna system 100 of Figure 1 over the operating frequency.
• variable capacitor for example, a tunable MEMS capacitor, a varactor diode and the like as discussed above.
• the variable capacitor may be used to replace the interdigital capacitor 145 on the radiating loop 140 as illustrated in Figure 1.
• S (Sn, S 22j S 21 ) parameters for an antenna system having different values of the capacitor will be discussed.
• the folded monopole antenna 105 is represented as antenna 1 and the loop antenna 110 is represented as antenna 2.
• the graph illustrates S values (Sn, S 22> S 21 ) for capacitor values of .55PF, .5PF and .45 PF.
• S n , .55PF; S n ,.5PF; and S n ,.45PF are indicated by curves 405, 406 and 407, respectively.
• S 2) , .55PF; S 2 i,.5PF; and S 2 i,.45PF are indicated by curves 410, 411 and 412, respectively.
• S 22 ,.5PF; and S 22 ,.45PF are indicated by curves 415, 416 and 417, respectively.
• the resonant frequency of the magnetic loop varies with the value of the capacitor.
• SI 1 ⁇ -lOdB the resonant frequency of the magnetic loop
• the performance of the monopole antenna 105 is not influenced during the tuning of the loop antenna 110, which makes the frequency tuning easier to achieve.
• FIG 5 a diagram of a co-located antenna system 500 in accordance with some embodiments of the present inventive concept will be discussed.
• the two antennas 505' and 510' can be co-located at one end of the PCB 515.
• FIG. 6 a graph of antenna scattering parameters (S l l5 S2 2 , S 12 and S 21 ) versus frequency that may be generated by an operational simulation of the antenna system of Figure 5 will be discussed.
• the folded monopole antenna 505' is represented as antenna 1 and the loop antenna 510' is represented as antenna 2.
• Sn indicated by curve 605 represents radiating element 520 of the folded monopole
• S 22 indicated by curve 615 represents radiating element 540 of the loop antenna 510' of Figure 5 and is a measure of how much power (dB) is reflected back to transceiver circuitry connected thereto.
• S 21 S 12 (indicated by Curve 610) represents the coupling that occurs between the antenna feed ports of the radiating elements 520 and 540.
• a null in isolation can be achieved at the resonant frequency.
• the radiation patterns for both antennas are similar to those of the antenna system of Figure 1. The efficiencies may be about
• the terminal 950 includes an antenna system 900, a transceiver 940, a processor 927, and can further include a conventional display 908, keypad 902, speaker 904, mass memory 928, microphone 906, and/or camera 924, one or more of which may be electrically grounded to the same ground plane (e.g., ground plane 115 of Figure 1 or 515 of Figure 5) as the antenna 900.
• the antenna 900 may be structurally configured as shown for the antenna system 100 of Figure 1 or co- located antenna system 500 of Figure 5, or may be configured in accordance with various other embodiments of the present inventive concept.
• the transceiver 940 may include transmit/receive circuitry (TX/RX) that provides separate communication paths for supplying/receiving RF signals to different radiating elements of the antenna system 900 via their respective RF feeds. Accordingly, when the antenna system 900 includes two antenna elements, such as shown in Figures 1 and 5, the transceiver 940 may include two transmit/receive circuits 942,944 connected to different ones of the antenna elements via the respective RF feeds 125/525 and 135/535.
• TX/RX transmit/receive circuitry
• the transceiver 940 in operational cooperation with the processor 927 may be configured to communicate according to at least one radio access technology in two or more frequency ranges.
• the at least one radio access technology may include, but is not limited to, WLAN (e.g., 802.11), WiMAX (Worldwide Interoperability for Microwave Access), TransferJet, 3GPP LTE (3rd Generation Partnership Project Long Term Evolution), Universal Mobile Telecommunications System (UMTS), Global Standard for Mobile (GSM) communication, General Packet Radio Service (GPRS), enhanced data rates for GSM evolution (EDGE), DCS, PDC, PCS, code division multiple access (CDMA), wideband- CDMA, and/or CDMA2000.
• WLAN e.g., 802.11
• WiMAX Worldwide Interoperability for Microwave Access
• TransferJet 3GPP LTE (3rd Generation Partnership Project Long Term Evolution
• UMTS Universal Mobile Telecommunications System
• GSM Global Standard for Mobile
• GPRS General Packet Radio Service
• EDGE enhanced data

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• 2011
  • 2011-06-30 EP EP11744066.9A patent/EP2727181A1/de not_active Withdrawn
  • 2011-06-30 US US14/115,461 patent/US9531084B2/en not_active Expired - Fee Related
  • 2011-06-30 WO PCT/IB2011/001532 patent/WO2013001327A1/en active Application Filing

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